Which of the following best describes the flow of electrons in the acid-catalyzed dimerization of $(CH_3)_2C = CH_2$?

Chlorination can be done on

Answer the following questions:
$(i)$ What is the bond length of $C-C$,$C=C$,and $C\equiv C$?
$(ii)$ What will be the effect on bond length as bond multiplicity increases?
$(iii)$ What is the relation between reactivity of compound,bond strength and bond order between two carbon atoms?
$(iv)$ What is the rate of reaction of $Cl_2, Br_2,$ and $I_2$ with $CH_2=CH_2$?
$(v)$ What is the difference between $2-$butyne and $1-$butyne? By which test can we distinguish between these two?
$(vi)$ Which real product is obtained on hydrolysis of alkyne? Why?
$(vii)$ Give the structure and $IUPAC$ name:
$(a)$ Vinyl chloride
$(b)$ Vinyl cyanide
$(c)$ Glyoxal
$(d)$ Silver acetylide
$(e)$ Diacetyl
$(f)$ Glycol

Product $(B)$ of the reaction is

The product of the reaction is:

What are $B$ and $C$ respectively in the following set of reactions?
$C \xleftarrow[\Delta]{Zn} 1,2-\text{dibromopropane}$ $\xrightarrow[\text {(ii) } NaNH_2]{\text {(i) alc. } KOH} A$ $\xrightarrow[\text { Catalyst }]{\text { Lindlar }} B$